Current below the knee (trans-tibial) prostheses utilize elaborate springs and elastomers to store and dissipate energy during ambulation. While these designs are functional, they do not allow for energy input into the system which is necessary for reproducing normal human gait. This proposal investigates a new approach to the design of prostheses. The proposed bionic trans-tibial prosthesis uses a simple mechanism in conjunction with a spring and an electric motor that can more appropriately reproduce ankle moments while simultaneously keeping actuator power and energy consumption low. It is based upon preliminary theoretical research and a rough experimental prototype which shows such an approach is feasible. To ascertain if such a device is both feasible and functional from an amputee's perspective, a full working prototype will be created and compared to two standard dynamic response feet. The prosthesis will be tested on a modified test stand to adequately compare the performance of the prototype to these two standard feet and ensure amputee safety. The prototype prosthesis will then be fitted onto three test subjects who will ambulate with both the standard passive prosthesis and the powered prosthesis. During this testing, the research team will perform standard motion analysis to gain invaluable understanding of both the dynamic performance and the users'acceptance. The results of this experiment will be utilized to finalize the design which will then be tested under a subsequent R01 funding mechanism. PUBLIC HEALTH RELEVANCE: This research creates a new design paradigm of below-the-knee prostheses. These bionic prostheses will aid lower limb amputees to lead more active and productive lives.